1. Field of the Invention
The present invention relates to a nitride semiconductor laser element, and more particularly relates to a nitride semiconductor laser element having a protective film with a particular structure on at least one end face of the cavity.
2. Background Information
With a nitride semiconductor laser element, end faces of the cavity formed by RIE (reactive ion etching) or cleavage has a narrow bandgap energy, so absorption of the exiting light occurs at the end face, this absorption generates heat at the end face, and problems such as a short service life are encountered in trying to obtain a high-output laser. Consequently, there has been proposed, for example, a method for manufacturing a high-output semiconductor laser in which a silicon oxide or nitride film is formed as a protective film on the cavity end face (see, for example, Japanese Laid-Open Patent Application H10-70338). This protective film functions as a window layer, and suppresses optical absorption at the cavity end face.
However, even if a material of the protective film that can suppress optical absorption at the end face of the cavity is used in a nitride semiconductor laser element, differences in the lattice constant of the nitride semiconductor can produce cracks in the nitride semiconductor layer and the protective film, or separation of the protective film can occur, both of which are problems that preclude the desired function from being realized.